Vim development workflow: 'errorformat' + ":make"

Gintautas, it seems you're approaching the problem in a non-vim way. Have a look at the 'errorformat' option (":help 'errorformat') and more generally at the quickfix mechanism (":help quickfix").

It seems to me that what you want to do should be solved with a Makefile invoking the unit tests (at that point executing ":make" inside vim would trigger the testing) + an appropriate 'errorformat' setting which recognize the strings returned by your tests.